The invention relates to a device for working of tree trunks to produce squared timbers from them with a machining center, with a feed section which is located in front of the machining center viewed in the machining direction, and with a delivery section which viewed in the machining direction is located after the machining center, and with grippers which can be moved relative to the machining center on carriages in the feed section for pushing the tree trunks to the machining center.